D. Hesse

Publications (112)169.53 Total impact

• Source

  Available from: Sunggi Baik

  Article: Fabrication of epitaxial nanostructured ferroelectrics and investigation of their domain structures

  H. Han, K. Lee, W. Lee, M. Alexe, D. Hesse, S. Baik
  [show abstract] [hide abstract]
  ABSTRACT: Nanostructured ferroelectrics are important objects for studies on ferroelectric size effects as well as for applications to memory devices with ultra-high memory density. In the present article, we introduce several approaches for the synthesis of confined ferroelectrics with sizes in and below the hundreds of nanometer range, including top-down processes like e-beam lithography, self-assembly methods like chemical solution deposition, and growth by pulsed laser deposition using stencil masks. Furthermore, the ferroelectric domain structure of part of these nanostructures is investigated by means of synchrotron X-ray diffraction, and its contribution to the ferroelectric properties is discussed.
  Journal of Materials Science 04/2012; 44(19):5167-5181. · 2.02 Impact Factor
• Source

  Available from: research.sabanciuniv.edu

  Article: Influence of long-range dipolar interactions on the phase stability and hysteresis shapes of ferroelectric and antiferroelectric multilayers

  I. B. Misirlioglu, L. Pintilie, M. Alexe, D. Hesse
  [show abstract] [hide abstract]
  ABSTRACT: Phase transition and field driven hysteresis evolution of a two-dimensional Ising grid consisting of ferroelectric–antiferroelectric multilayers that take into account the long range dipolar interactions were simulated by a Monte–Carlo method. Simulations were carried out for a 1+1 bilayer and a 5+5 superlattice. Phase stabilities of components comprising the structures with an electrostatic-like coupling term were also studied. An electrostatic-like coupling, in the absence of an applied field, can drive the ferroelectric layers toward 180° domains with very flat domain interfaces mainly due to the competition between this term and the dipole–dipole interaction. The antiferroelectric layers do not undergo an antiferroelectric-to-ferroelectric transition under the influence of an electrostatic-like coupling between layers as the ferroelectric layer splits into periodic domains at the expense of the domain wall energy. The long-range interactions become significant near the interfaces. For high periodicity structures with several interfaces, the interlayer long-range interactions substantially impact the configuration of the ferroelectric layers while the antiferroelectric layers remain quite stable unless these layers are near the Neel temperature. In systems investigated with several interfaces, the hysteresis loops do not exhibit a clear presence of antiferroelectricity that could be expected in the presence of anti-parallel dipoles, i.e., the switching takes place abruptly. Some recent experimental observations in ferroelectric–antiferroelectric multilayers are discussed where we conclude that the different electrical properties of bilayers and superlattices are not only due to strain effects alone but also due to long-range interactions. The latter manifests itself particularly in superlattices where layers are periodically exposed to each other at the interfaces.
  Journal of Materials Science 04/2012; 44(19):5354-5363. · 2.02 Impact Factor
• Source

  Available from: mpi-halle.de

  Article: Ultrafast structural dynamics of perovskite superlattices

  M. Woerner, C. v. Korff Schmising, M. Bargheer, N. Zhavoronkov, I. Vrejoiu, D. Hesse, M. Alexe, T. Elsaesser
  [show abstract] [hide abstract]
  ABSTRACT: Femtosecond x-ray diffraction provides direct insight into the ultrafast reversible lattice dynamics of materials with a perovskite structure. Superlattice (SL) structures consisting of a sequence of nanometer-thick layer pairs allow for optically inducing a tailored stress profile that drives the lattice motions and for limiting the influence of strain propagation on the observed dynamics. We demonstrate this concept in a series of diffraction experiments with femtosecond time resolution, giving detailed information on the ultrafast lattice dynamics of ferroelectric and ferromagnetic superlattices. Anharmonically coupled lattice motions in a SrRuO3/PbZr0.2Ti0.8O3 (SRO/PZT) SL lead to a switch-off of the electric polarizations on a time scale of the order of 1ps. Ultrafast magnetostriction of photoexcited SRO layers is demonstrated in a SRO/SrTiO3 (STO)SL.
  Applied Physics A 04/2012; 96(1):83-90. · 1.63 Impact Factor
• Source

  Available from: ArXiv

  Article: Magnetic properties of Pr0.7Ca0.3MnO3/SrRuO3 superlattices

  M. Ziese, I. Vrejoiu, E. Pippel, E. Nikulina, D. Hesse
  [show abstract] [hide abstract]
  ABSTRACT: High-quality Pr _0.7 Ca _0.3 MnO ₃/ SrRuO ₃ superlattices were fabricated by pulsed laser deposition and were investigated by high-resolution transmission electron microscopy and superconducting quantum interference device magnetometry. Superlattices with orthorhombic and tetragonal SrRuO ₃ layers were investigated. The superlattices grew coherently; in the growth direction Pr _0.7 Ca _0.3 MnO ₃ layers were terminated by MnO ₂ and SrRuO ₃ layers by RuO ₂ -planes. All superlattices showed antiferromagnetic interlayer coupling in low magnetic fields. The coupling strength was significantly higher for orthorhombic than for tetragonal symmetry of the SrRuO ₃ layers. The strong interlayer exchange coupling in the superlattice with orthorhombic SrRuO ₃ layers led to a magnetization reversal mechanism with a partially inverted hysteresis loop.
  Applied Physics Letters 04/2011; · 3.84 Impact Factor
• Source

  Available from: ArXiv

  Article: Orthorhombic to tetragonal transition of SrRuO3 layers in Pr0.7Ca0.3MnO3/SrRuO3 superlattices

  M. Ziese, I. Vrejoiu, E. Pippel, E. Nikulina, D. Hesse
  [show abstract] [hide abstract]
  ABSTRACT: High-quality Pr0.7Ca0.3MnO3/SrRuO3 superlattices with ultrathin layers were fabricated by pulsed laser deposition on SrTiO3 substrates. The superlattices were studied by atomically resolved scanning transmission electron microscopy, high-resolution transmission electron microscopy, resistivity and magnetoresistance measurements. The superlattices grew coherently without growth defects. Viewed along the growth direction, SrRuO3 and Pr0.7Ca0.3MnO3 layers were terminated by RuO2 and MnO2, respectively, which imposes a unique structure to their interfaces. Superlattices with a constant thickness of the SrRuO3 layers, but varying thickness of the Pr0.7Ca0.3MnO3 layers showed a change of crystalline symmetry of the SrRuO3 layers. At a low Pr0.7Ca0.3MnO3 layer thickness of 1.5 nm transmission electron microscopy proved the SrRuO3 layers to be orthorhombic, whereas these were non-orthorhombic for a Pr0.7Ca0.3MnO3 layer thickness of 4.0 nm. Angular magnetoresistance measurements showed orthorhombic (with small monoclinic distortion) symmetry in the first case and tetragonal symmetry of the SrRuO3 layers in the second case. Mechanisms driving this orthorhombic to tetragonal transition are briefly discussed.
  02/2011;
• Source

  Available from: Lifeng Liu

  Conference Proceeding: Vortex polarization states in nanoferroelectrics

  B.J. Rodriguez, X.S. Gao, L.F. Liu, W. Lee, I.I. Naumov, A.M. Bratkovsky, D. Hesse, M. Alexe
  [show abstract] [hide abstract]
  ABSTRACT: Two-dimensional arrays of ferroelectric lead zirconate titanate (PZT) nanodots fabricated using pulsed laser deposition (PLD) through ultrathin anodic aluminum oxide (AAO) membrane stencil masks have been investigated using piezoresponse force microscopy (PFM). Core-polarization states, which may indicate the presence of quasi-toroidal polarization ordering, have been observed. Existing theoretical data have been used to determine the signature of a vortex polarization state in a PFM experiment and compared to the measured data.
  Optoelectronic and Microelectronic Materials and Devices (COMMAD), 2010 Conference on; 01/2011
• Source

  Available from: Lifeng Liu

  Article: Bubble polarization domain patterns in periodically ordered epitaxial ferroelectric nanodot arrays

  X S Gao, F Xue, M H Qin, J M Liu, B J Rodriguez, L F Liu, M Alexe, D Hesse
  [show abstract] [hide abstract]
  ABSTRACT: In this work, bubble polarization domains in periodically ordered ferroelectric Pb(Zr(0.4)Ti(0.6))O(3) nanodot arrays and their formation mechanisms have been investigated by piezoresponse force microscopy (PFM) and Monte-Carlo simulations. The PFM observations reveal the coexistence of single domain and apparent bubble domain patterns within the same nanodot array, which also exhibit dissimilar polarization reversal processes. The formation of various polarization configurations can be accounted for by the interplay of various factors, such as polarization anisotropy and depolarization field. Using Monte-Carlo simulation, we are able to reproduce bubble and single domains and further predict that these patterns can be tailored by varying the nanodot parameters, including dot height, aspect ratio, etc. (C) 2011 American Institute of Physics. [doi:10.1063/1.3623766]
  Journal of Applied Physics 01/2011; 110(5). · 2.17 Impact Factor
• Source

  Available from: Roland Mattheis

  Article: Influence of slanted nanostripe edges on the dynamics of magnetic domain walls

  S. Glathe, M. Zeisberger, R. Mattheis, D. Hesse
  [show abstract] [hide abstract]
  ABSTRACT: We report a combined experimental and theoretical study on the influence of slanted nanostripe edges on the magnetic domain wall (DW) dynamics in permalloy nanostripes. The DWs show a significantly different behavior in the same sample depending on the magnetization configuration in the DW. We explain these characteristics via a difference of the stray field generated by the out-of-plane magnetization inside the DW in the nanostripe edge region during DW motion.
  Applied Physics Letters 09/2010; 97(11):112508-112508-3. · 3.84 Impact Factor
• Source

  Available from: mpi-halle.de

  Article: Inverted hysteresis and giant exchange bias in La0.7Sr0.3MnO3/SrRuO3 superlattices

  M. Ziese, I. Vrejoiu, D. Hesse
  [show abstract] [hide abstract]
  ABSTRACT: The magnetization reversal mechanisms in a La0.7Sr0.3MnO3/SrRuO3 superlattice with ultrathin individual layers were studied. Due to the strong exchange bias between La0.7Sr0.3MnO3 and SrRuO3 layers inverted hysteresis loops were observed at temperatures below 62 K; at higher temperatures the superlattice showed an unconventional reversal mechanism with the magnetically hard SrRuO3 layers switching first on reducing the magnetic field from saturation. These observations were corroborated by micromagnetic simulations and were interpreted as arising from interfacial Bloch walls.
  Applied Physics Letters 08/2010; 97(5):052504-052504-3. · 3.84 Impact Factor
• Source

  Available from: Marc Herzog

  Article: Ultrafast manipulation of hard x-rays by efficient Bragg switches

  M. Herzog, W. Leitenberger, R. Shayduk, R. M. van der Veen, C. J. Milne, S. L. Johnson, I. Vrejoiu, M. Alexe, D. Hesse, M. Bargheer
  [show abstract] [hide abstract]
  ABSTRACT: We experimentally demonstrate efficient switching of the hard x-ray Bragg reflectivity of a SrRuO ₃/ SrTiO ₃ superlattice by optical excitation of large-amplitude coherent acoustic superlattice phonons. The rocking curve changes drastically on a 1 ps timescale. The (0 0 116) reflection is almost extinguished (ΔR/R₀=-0.91) , while the (0 0 118) reflection increases by more than an order of magnitude (ΔR/R₀=24.1) . The change of the x-ray structure factor depends nonlinearly on the phonon amplitude, allowing manipulation of the x-ray response on a timescale considerably shorter than the phonon period. Numerical simulations for a superlattice with slightly changed geometry and realistic parameters predict a switching-contrast ratio ΔR/R₀ of 700 with high reflectivity.
  Applied Physics Letters 05/2010; · 3.84 Impact Factor
• Source

  Available from: P. Esquinazi

  Article: Tailoring magnetic interlayer coupling in La0.7Sr0.3MnO3/SrRuO3 superlattices.

  M Ziese, I Vrejoiu, E Pippel, P Esquinazi, D Hesse, C Etz, J Henk, A Ernst, I V Maznichenko, W Hergert, I Mertig
  [show abstract] [hide abstract]
  ABSTRACT: The magnetic interlayer coupling in La0.7Sr0.3MnO3/SrRuO3 superlattices was investigated. High quality superlattices with ultrathin La0.7Sr0.3MnO3 and SrRuO3 layers were fabricated by pulsed laser deposition. The superlattices grew coherently with Mn/Ru intermixing restricted to about one interfacial monolayer. Strong antiferromagnetic interlayer coupling depended delicately on magnetocrystalline anisotropy and intermixing at interfaces. Ab initio calculations elucidated that the antiferromagnetic coupling is mediated by the Mn-O-Ru bond. The theoretical calculations allowed for a quantitative correlation between the total magnetic moment of the superlattice and the degree of Mn/Ru intermixing.
  Physical Review Letters 04/2010; 104(16):167203. · 7.37 Impact Factor
• Article: Microstructural evolution of [PbZrxTi1-xO3/PbZryTi1-yO3](n) epitaxial multilayers (x/y=0.2/0.4, 0.4/0.6) - dependence on layer thickness

  Y. L. Zhu, S. J. Zheng, X. L. Ma, L. Feigl, M. Alexe, D. Hesse, I. Vrejoiu
  [show abstract] [hide abstract]
  ABSTRACT: The microstructure of ferroelectric [PbZrxTi1-xO3/PbZryTi1-yO3](n) epitaxial multilayers (x/y 0.2/0.4, 0.4/0.6) deposited on SrRuO3-coated SrTiO3 substrates by pulsed-laser deposition with different layer periodicity and layer thickness was characterized by means of transmission electron microscopy. Electron diffraction and contrast analysis revealed a very clear and well-separated layer sequence. The microstructures of PbZr0.2Ti0.8O3/PbZr0.4Ti0.6O3 and PbZr0.4Ti0.6O3/PbZr0.6Ti0.4O3 multilayers show a similar tendency in the dependence on the individual layer thickness. Whereas with thick individual layers, tetragonal a-domains are confined to specific layers of the two types of multilayers, below a certain critical thickness of the individual layers, a-domains extend over the whole film. This indicates a transition into a uniform tetragonal lattice and strain state of the whole multilayer. Increasing the layer periodicity further, the interfaces in PbZr0.4Ti0.6O3/PbZr0.6Ti0.4O3 multilayers become rough, and complex a-domain configurations appear.
  Philosophical Magazine 03/2010; 90(10):1359-1372. · 1.51 Impact Factor
• Source

  Available from: mpi-halle.de

  Article: Microstructural evolution of [PbZr x Ti1– x O3/PbZr y Ti1– y O3] n epitaxial multilayers (x/y = 0.2/0.4, 0.4/0.6)–dependence on layer thickness

  Y.L. Zhu, S.J. Zheng, X.L. Ma, L. Feigl, M. Alexe, D. Hesse, I. Vrejoiu
  [show abstract] [hide abstract]
  ABSTRACT: The microstructure of ferroelectric [PbZr x Ti1− x O3/PbZr y Ti1− y O3] n epitaxial multilayers (x/y = 0.2/0.4, 0.4/0.6) deposited on SrRuO3-coated SrTiO3 substrates by pulsed-laser deposition with different layer periodicity and layer thickness was characterized by means of transmission electron microscopy. Electron diffraction and contrast analysis revealed a very clear and well-separated layer sequence. The microstructures of PbZr0.2Ti0.8O3/PbZr0.4Ti0.6O3 and PbZr0.4Ti0.6O3/PbZr0.6Ti0.4O3 multilayers show a similar tendency in the dependence on the individual layer thickness. Whereas with thick individual layers, tetragonal a-domains are confined to specific layers of the two types of multilayers, below a certain critical thickness of the individual layers, a-domains extend over the whole film. This indicates a transition into a uniform tetragonal lattice and strain state of the whole multilayer. Increasing the layer periodicity further, the interfaces in PbZr0.4Ti0.6O3/PbZr0.6Ti0.4O3 multilayers become rough, and complex a-domain configurations appear.
  Philosophical Magazine. 03/2010; 90(10):1359-1372.
• Source

  Available from: Roland Mattheis

  Article: Switching of magnetic anisotropy in epitaxial CoFe2O4 thin films induced by SrRuO3 buffer layer

  X S Gao, D H Bao, B Birajdar, T Habisreuther, R Mattheis, M A Schubert, M Alexe, D Hesse
  [show abstract] [hide abstract]
  ABSTRACT: The magnetic anisotropy of epitaxial spinel ferrite CoFe2O4 films grown on SrTiO3 substrates by pulsed laser deposition can be reoriented by inserting a thin SrRuO3 buffer layer. Without SrRuO3, the CoFe2O4 films show a uniaxial anisotropy with the easy axis perpendicular to the film plane, while inserting a SrRuO3 buffer layer results in the switching of the easy axis into the in-plane orientation. This is associated with a tensile and a compressive strain for the films without and with buffer layer, respectively, which is also correlated with the different density of interfacial misfit dislocations. As a result, the ferrite films can be effectively tailored by using SrRuO3.
  Journal of Physics D Applied Physics 08/2009; 42(17):175006. · 2.54 Impact Factor
• Source

  Available from: mpi-halle.de

  Article: Chromium doping of epitaxial PbZr0.2Ti0.8O3 thin films

  L. Feigl, E. Pippel, L. Pintilie, M. Alexe, D. Hesse
  [show abstract] [hide abstract]
  ABSTRACT: Epitaxial ferroelectric PbZr _0.2 Ti _0.8 O ₃ thin films were grown by pulsed laser deposition. PbZr _0.2 Ti _0.8 O ₃ was doped with Cr acting as acceptor ion. Microstructural characterization was performed by (high resolution) transmission electron microscopy. The voltage dependence of polarization, dielectric constant, and leakage current were measured with respect to the Cr content. To derive the electronic properties, PZT was considered as a wide-gap semiconductor which allows treating the metal-PZT interface as a Schottky contact. The Cr was found to facilitate the elastic relaxation of the film. Furthermore, the leakage current was increased through a reduction of the Schottky barrier.
  Journal of Applied Physics 07/2009; · 2.17 Impact Factor
• Article: Impact of high interface density on ferroelectric and structural properties of PbZr0.2Ti0.8O3/PbZr0.4Ti0.6O3 epitaxial multilayers

  L. Feigl, S. J. Zheng, B. I. Birajdar, B. J. Rodriguez, Y. L. Zhu, M. Alexe, D. Hesse
  [show abstract] [hide abstract]
  ABSTRACT: Multilayers consisting of two tetragonal compositions PbZr0.2Ti0.8O3 and PbZr0.4Ti0.6O3 were deposited onto a SrRuO3 electrode grown on a vicinal (100) SrTiO3 substrate. It has been shown by extensive structural investigations comprising transmission electron microscopy in conventional and high resolution mode, reciprocal space mapping and piezoresponse force microscopy that with decreasing layer thickness a transition from a-domains confined to individual layers to a-domains propagating through the whole film takes place. This is caused by the formation of a common strain state of all layers which is responsible for the observed enhancement of the electrical properties. These show a maximum in the product of remanent polarization and dielectric constant at a certain density of interfaces. If the interface density becomes too high the lattice distortion accompanying each interface deteriorates the properties of the multilayer structure.
  Journal of Physics D Applied Physics 04/2009; 42(8):085305. · 2.54 Impact Factor
• Source

  Available from: mpg.de

  Article: Effect of a single dislocation in a heterostructure layer on the local polarization of a ferroelectric layer.

  C L Jia, S B Mi, K Urban, I Vrejoiu, M Alexe, D Hesse
  [show abstract] [hide abstract]
  ABSTRACT: We study, on an atomic scale, the influence of a single dislocation in a SrTiO3 sublayer on the local ferroelectric polarization of the neighboring ferroelectric PbZr0.2Ti0.8O3 (PZT) sublayer in an epitaxial SrTiO3/PbZr0.2Ti0.8O3/SrTiO3 three-layer heterostructure. The strain field of the dislocation in the SrTiO3 layer propagates across the interface into the PZT layer and leads to a strong variation of the c-lattice parameter of the PZT layer. Accompanying a strong reduction of the c-lattice parameter, the off-center displacements of the Zr/Ti atoms away from the center of the oxygen octahedra are also strongly decreased, resulting in a decrease of the local spontaneous polarization by up to 48%.
  Physical Review Letters 04/2009; 102(11):117601. · 7.37 Impact Factor
• Source

  Available from: uripore.com

  Article: Vortex polarization states in nanoscale ferroelectric arrays.

  B J Rodriguez, X S Gao, L F Liu, W Lee, I I Naumov, A M Bratkovsky, D Hesse, M Alexe
  [show abstract] [hide abstract]
  ABSTRACT: Two-dimensional arrays of ferroelectric lead zirconate titanate (PZT) nanodots were fabricated using pulsed laser deposition through ultrathin anodic aluminum oxide membrane stencil masks. The static distribution of polarization configurations was investigated using in- and out-of-plane piezoresponse force microscopy (PFM). The observed presence of an in-plane polarization component in nominally (001) oriented PZT suggests the existence of a significant deviation from the regular tetragonal structure that allows the formation of complex core-polarization states. Core-polarization states may indicate the presence of quasi-toroidal polarization ordering. The experimental results are compared with a theoretical model to determine the fingerprint of a vortex polarization state in PFM.
  Nano Letters 03/2009; 9(3):1127-31. · 13.20 Impact Factor
• Chapter: Ultrafast Structural Dynamics of Polar Solids Studied by Femtosecond X-Ray Diffraction

  T. Elsaesser, C. von Korff Schmising, N. Zhavoronkov, M. Bargheer, M. Woerner, M. Braun, P. Gilch, W. Zinth, I. Vrejoiu, D. Hesse, M. Alexe
  [show abstract] [hide abstract]
  ABSTRACT: We discuss recent progress in ultrafast x-ray diffraction, addressing photoinduced structural dynamics in ferroelectric superlattices and polar molecular crystals. Elongations of coupled phonon modes affecting ferroelectric polarizations and structural changes connected with the solvation of molecular dipoles are determined quantitatively.
  12/2008: pages 101-103;
• Chapter: Femtosecond X-ray Diffraction Study of the Ultrafast Coupling between Magnetization and Structure in the Ferromagnet SrRuO3

  C. v Korff Schmising, M. Bargheer, A. Harpoeth, N. Zhavoronkov, Z. Ansari, M. Woerner, T. Elsaesser, I. Vrejoiu, D. Hesse, M. Alexe
  [show abstract] [hide abstract]
  ABSTRACT: Femtosecond optical excitation of magnetically ordered SrRuO3 nanolayers leads to an ultrafast demagnetization and a concomitant magnetoelastic contractive stress. The resulting ultrafast structural response of the sample is imaged by femtosecond X-ray diffraction.
  12/2008: pages 107-109;